1. Field of the Invention
The present invention relates communication networks and, more particularly, to a controller and a method for controlling communication services for applications on a physical network.
2. Description of the Related Art
Many networks particularly require a predictable operation with precise timings and a high level of reliability. This is especially true for industrial networks. In this regard, “industrial network” preferably refers to Ethernet/IP-based networks in factory automation, traffic control, machine-to-machine, Supervisory control and data acquisition (SCADA) application areas.
Current internet and local area network technologies cannot fulfill those requirements. Many conventional technical extensions in the form of industrial communication standards try to solve these issues, such as the PROFINET standard. Basically, for all of these standards, the same steps have to apply. In a first step, the applications have to be planned. In a second step, requirements have to be derived. In a third step, the network has to be planned. In a fourth step, the network has to be rolled out and configured. In a fifth step, the network has to be started for providing the applications.
One problem with this procedure is the lack of flexibility under tight coupling of the application planning in network configuration and operation. If something changes in the physical network or in one of the applications, at least some of the steps have to be repeated. This may create extra costs due to manual re-planning. Further, this may be error-prone. Furthermore, it may be hard to use non-industrial technologies as a base for products in industrial networks. In particular, the evolution of standard Internet/LAN technologies is difficult to be integrated within an industrial communication technology such as PROFINET. One of these reasons is the required development costs in terms of hardware, like application specific integrated circuits (ASICs), such as the case within PROFINET. Any technological improvement in the Institute of Electrical and Electronic Engineers (IEEE) standard Ethernet requires large development costs to integrate this extension within PROFINET. Further, this might lead to several generations of the same protocol that potentially cannot interoperate. In addition, the effect of a change on the standard might snow-ball, because PROFINET covers not only networking issues, but also end-devices, middleware and engineering tools that interact with the PROFINET-capable devices and networks. In addition, mixing products from different standards, with sometimes very different capabilities in the same network, is typically difficult or not possible because conventional planning tools cannot work with heterogeneous standards.
A further problem is the fact that many applications from different stack holders may compete for resources and have to be shielded from each other for security and management reasons (multi-tenancy). The share of the network allocated to each application has to be done on-demand and without physically extending the network. The service that the network provides to the applications has to provide guarantees on the one hand, but it also shall enforce restrictions (policy control).
Further, quality of service, resilience and routing/forwarding has to be managed in the physical network.
For each above-discussed partial problem, separate technology developments exist in the Internet and local area networks.
The present partial solutions within the industrial fields may be categorized into the following:
1) Use of different physical networks. This approach, while still commonly used, provides no flexibility and creates extra costs for hardware.
2) The use of virtualization combined with over-dimensioning of the network by setting up a pre-defined and static series of subnets and LANs around a given application (e.g., a control application of a factory cell). This cellular approach also may be less effective neither in allowing inter-cell communication nor in enabling rational network deployment.3) Industrial extensions to Ethernet protocols to include needs of industrial communication. This solution, however, lacks flexibility, is not suited for interoperability, and has created specialized niche products that have evolved as standalone standards such as Profinet. Those industrial standards typically cannot shield non-industrial applications from each other and must use other means as described in publication [2] to do so.4) Traffic engineering and Quality of Service (QoS) dimensioning of the network, which is the approach often found in telecommunication networks and used by internet service providers. This allows a certain control over the owned network that is providing communication as a service to multiple tiers. This approach is, however, not as appropriate to the industrial applications, due to the granularity and complexity in defining Service Level Agreements (SLAs) for each user. This approach is also based on some protocols and specified for larger hardware (such as routers supporting RSVP, or MPLS switches). Thus, existing technologies cannot be used for industrial networks, here.
Conventional methods and devices for controlling communication services for applications on a physical network are described in publications [1] to [14].